1. Field of the Invention
This invention relates to a camera having a lens barrier mechanism for covering the front of a lens and thereby protecting the lens.
2. Description of the Related Art
In an optical apparatus, especially in a silver-film camera or a digital camera that can be used as a portable camera, a lens barrier mechanism is provided at the front end of a lens barrel, in order to prevent an image-taking lens from being dirtied or scratched when no image-taking is performed (for example, when a power source is in OFF state).
Recently, demands to reduce the size of cameras have been made, and, in order to meet this demand, an attempt has been made to reduce the size of a lens barrel that holds an image-taking lens, in addition to the size reduction of a camera. Accordingly, it is necessary to reduce the size of a lens barrier mechanism mounted in the lens barrel.
Additionally, in order to possess superior product advantages, it is necessary not only to reduce the size of the camera but also to reduce manufacturing costs, and therefore it is also necessary to achieve cost reductions of the lens barrier mechanism mounted in the lens barrel as well as the size reduction thereof. As a result, various techniques have been developed to satisfy the aforementioned demands.
In Japanese Laid-Open No. H7-5545, the present applicant proposes a camera lens barrier mechanism suitable for an oblong screen. This lens barrier mechanism has an opening lengthened in a lateral direction, a rotary barrier plate that is rotated by 90 degrees on a lens optical axis when a barrier is closed, and a pair of upper and lower barrier blades that can rise and fall and can retract into a space above the upper edge of a hole of the rotary barrier plate and into a space under the lower edge of the hole thereof, respectively, when the barrier is opened.
Further, in Japanese Laid-Open No. H9-211536, there is proposed a barrier device that can prevent an increase in thickness in the direction of the optical axis of a barrier device body, thereby making the device compact.
This barrier device includes a barrier member for covering the front of a image-taking lens in a closed state, a driving member for opening and closing the barrier member, and an elastic member for absorbing a run out movement of the driving member with respect to the barrier member. The elastic member is incorporated into the inside of the barrier member. According to this publication, a compact lens barrier device is provided.
However, the lens barrier mechanism proposed in Japanese Laid-Open No. H7-5545 is at a disadvantage in the fact that the number of parts for driving the lens barrier mechanism increases, thereby leading to a rise in the cost of the camera.
On the other hand, in the barrier device proposed in Japanese Laid-Open No. H9-211536, the number of parts that constitute the device is small, and the thickness in the direction of the optical axis of the device body diminishes. However, since the shapes of the parts (for example, the shape of a primary barrier 1 and that of a sub-barrier 2 in this publication) are different from each other, a plurality of molds must be prepared when the parts are manufactured, and great expense for the molds and for the parts is required. As a result, to its disadvantage, the manufacturing costs of the barrier device rise.
Another problem of the barrier device disclosed in this publication is the fact that the rotational shafts of the two barriers (i.e., the primary barrier 1 and the sub-barrier 2 in this publication) are disposed near each other, and therefore a great retraction space is required when the barriers are retracted from an opening, thereby enlarging the barrier device in the radial direction.
It is therefore an object of the present invention to solve the aforementioned problems and to provide a camera capable of being made compact and capable of reducing costs.
The present invention is characterized in that a camera includes a hold barrel member which holds an image-taking optical unit; a barrier member, disposed on a subject side of the hold barrel member, which opens and closes a substantially rectangular opening; and a barrier driving member, disposed between the barrier member and the hold barrel member, which drives the barrier member in such a way so as to rotate on an optical axis of the image-taking optical unit. And the hold barrel member forms a long side part of the opening, and the barrier driving member forms a short side part of the opening in a state in which the barrier member opens the opening.
Preferably, the barrier driving member also forms a corner part of the opening.
Preferably, the camera further includes a spring, one end of which is connected to the barrier member and the other end of which is connected to the barrier driving member. The spring is disposed in a thickness in the direction of the optical axis of the barrier driving member.
Preferably, when the hold barrel member is moved into the camera body, the barrier driving member rotates on the optical axis, and the barrier driving member drives the barrier member so as to close the opening.
Preferably, when the hold barrel member is moved out from the camera body, the barrier driving member rotates on the optical axis, and the barrier driving member drives the barrier member so as to open the opening.
Preferably, the barrier member includes a pair of barrier blades that rotate on a predetermined axis disposed at the hold barrel member.
Further features and objects will become apparent from the drawings and descriptions provided below.